When the game is played in the attic Judy tells Sarah that she can win if she rolls a twelve, but she only rolls a three. On her next turn Allen says she can win with a seven, however 12 minus 3 means she would have needed a nine.
When Mr. and Mrs. Parish in the beginning of the movie are leaving for the evening, they are in the car and talking for a moment and the car is not running. Then Mr. Parish has his left hand on the steering wheel and his right hand on the gearshift, and then the motor is started. He could not start the car without turning the key, and he does not have a hand on the key.
When the EMTs are pulling the woman bitten by a mosquito out of her car, she is wearing boots which come to mid-calf. In the next shot where they are putting her into the ambulance, her legs are bare and she is wearing pumps on her feet.
When young Alan heads down the stairs of the factory to go face the bullies, he turns to look at the machine after Carl's shoe breaks it, and two ladies walk up the stairs. The shot cuts to Samuel demanding who is responsible, and when it cuts back to Alan, the same ladies walk up the stairs again.
In the store scene, while the hunter is under the paint, the cop takes his gun. The gun is also seen in the cops car when he drives away. At the end of the movie, the hunter shows up with the gun in his hand.
When Alan is startled by the grandfather clock and drops the dice, one die reads two, and the other, three. When his game piece starts moving in the next shot, it is apparent that neither die read two.
When Aunt Nora backs into the door in awe of her house being covered in vines, the claw marks are returned again; after opening the door, discovering the lion, and closing it again, the claw marks have, again, disappeared.
When the aunt flags down Carl to ask for a ride home, he's wearing his seat belt. When the vine attacks him and he has to jump out of the car, he does so without reaching over to unbuckle his seat belt.
When Allen opens the chest containing the board game, he reaches in and wipes some of the sand from the top. The scene cuts away and when the scene cuts back he lifts the game out, with the sand undisturbed.
There were 31 spaces on the game for each player from start to finish, main reason for other goofs mentioned in regards to this subject, but the biggest being Alan couldn't have finished when he did, since his rolls were: 5~?~7~3, and the second roll couldn't have been any higher than 11.
In the beginning of the movie, when Allen is fighting the lion, the kids are seen running behind him into the other room. Allen then traps the lion in that room and finds the kids hidden in the closet.
At the end of the movie when Van Pelt shoots Allen, the bullet never reaches Allen because it starts to disappear into the tornado along with the rifle that Van Pelt purchased at the store. Both the rifle and bullet are not from the game like the animals, Van, vines, therefore it should not have disappeared.
After Sarah gets rejected from the ATM, Van Pelt steals the game from Peter. In the rush, Peter steals it back and runs away. The driver of the second car (that almost hits him) appears to get out. However, after a cut scene of the stampeding animals, we see Peter run towards the open driver's door. As the camera turns, we see a foot under the door, which quickly retracts back into the car. The person is not seen inside the car, as Peter hides in the driver's seat as the animals crush the car.
In the scene after the brakes go out in the police car and it crashes into the store, the policeman simply refills the master cylinder with brake fluid to fix the brakes. The previous scene showed that there was a hole in the line that released fluid, which would cause the brakes to not work again, yet the policeman continues to use the brakes with no ill-effect.
The monkey is able to start the policeman's car by turning the key, and shift into (presumably) "drive," then he goes down in the seat to press the gas pedal. He is able to turn the key, start the engine, and shift into "drive" all without holding the brake pedal (he can't reach it until he moves down into the pedal area), which would be required for all three of these things in most automatic transmission vehicles.
All the animals in the herd of elephants, zebras, rhinos, and such seem to always stay together as they run at different speeds. Do the zebras and smaller animals constantly stop every now and then to let the others catch up?
When Alan asks Carl what year it is, Carl thinks he's asking about his car, and he said it was brand new. When Judy clarifies, she states the current year is 1995. Carl's car is at least three years old when this movie takes place, since the Chevy Caprice's skirted rear wheel wells were replaced with rounded wheel wells on models after 1992 so the car is not brand new.
When the mosquito is on the windshield, Alan refers to it as "he". Only female mosquitoes bite, not males. However arguably, many people do not know this and considering Allan never even finished the sixth grade, it could be presumed that he didn't know either (or the other two children for that matter).
At the end of the movie, the kids lock up Jumanji and throw it into the river. Jumanji was later found with no locks on it at all. However, the kids threw the game into the river in the year 1969. Presumably the final scene on the beach is set in the year 1995 as the previous "Christmas party" scene would indicate. It is entirely possible over the 26-year span ('69-'95) that the game had been found and played by others who didn't lock it up.
It's strange that when the game is finished, all the wild animals (as well as Van Pelt) get sucked back into the game, yet the wild plants and vines don't seem to. (For that matter, we don't even see the pelicans, monkeys, spiders or crocodile inside the "tornado" either.)